Update Network & internet->Wi-Fi to use MasterSwitchPreference.

- Add a preference controller for Network & internet->Wi-Fi to control
  the preference toggling and summary update.
- Refactor WifiSettings and WifiEnabler to share code between the new
  wifi preference controller and the wifi setting.
- Refactor BluetoothSummaryHelper to have a common base class with the
  WifiSummaryHelper.
- Rename the summary helper to summary updater.

Bug: 34280769
Test: make RunSettingsRoboTests
Change-Id: I00ebfc161bcef89331bb41ba405ed8cb8232d248

src/com/android/settings/widget/SummaryUpdater.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.widget;
+
+import android.content.Context;
+import android.text.TextUtils;
+
+/**
+ * Helper class that listens to settings changes and notifies client when there is update in
+ * corresponding summary info.
+ */
+public abstract class SummaryUpdater {
+
+    protected final Context mContext;
+
+    private final OnSummaryChangeListener mListener;
+    private String mSummary;
+
+    /**
+     * Interface definition for a callback to be invoked when the summary has been changed.
+     */
+    public interface OnSummaryChangeListener {
+        /**
+         * Called when summary has changed.
+         *
+         * @param summary The new summary .
+         */
+        void onSummaryChanged(String summary);
+    }
+
+    /**
+     * Constructor
+     *
+     * @param context The Context the updater is running in, through which it can register broadcast
+     * receiver etc.
+     * @param listener The listener that would like to receive summary change notification.
+     *
+     */
+    public SummaryUpdater(Context context, OnSummaryChangeListener listener) {
+        mContext = context;
+        mListener = listener;
+    }
+
+    /**
+     * Notifies the listener when there is update in summary
+     */
+    protected void notifyChangeIfNeeded() {
+        String summary = getSummary();
+        if (!TextUtils.equals(mSummary, summary)) {
+            mSummary = summary;
+            if (mListener != null) {
+                mListener.onSummaryChanged(summary);
+            }
+        }
+    }
+
+    /**
+     * Starts/stops receiving updates on the summary.
+     *
+     * @param register true if we want to receive updates, false otherwise
+     */
+    public abstract void register(boolean register);
+
+    /**
+     * Gets the summary. Subclass should checks latest conditions and update the summary
+     * accordingly.
+     *
+     * @return  the latest summary text
+     */
+    protected abstract String getSummary();
+
+}